Wafer to wafer bonding apparatus and wafer to wafer bonding method

Abstract

A wafer bonding apparatus including a first stage having a first surface and being configured to hold a first wafer on the first surface; a second stage having a second surface and being configured to hold a second wafer on the second surface facing the first surface; a first target image sensor on an outer portion of the first stage; a second target image sensor on an outer portion of the second stage; and a target portion on the first or second stage, the target portion having a target plate fixedly installed and spaced apart from the first or second target image sensor by a predetermined distance, wherein, in an alignment measurement of the first and second stages, the first and second stages are movable so that the first and second target image sensors face each other and the target plate is between the first and second target image sensors.

What is claimed is: 
     
       1. A wafer bonding apparatus, comprising:
 a first stage having a first surface, the first stage being configured to hold a first wafer on the first surface; 
 a second stage having a second surface, the second stage being configured to hold a second wafer on the second surface, the first surface and the second surface facing each other; 
 a first target image sensor on an outer portion of the first stage; 
 a second target image sensor on an outer portion of the second stage; 
 a target portion on the first stage or the second stage, the target portion having a target plate fixedly installed and spaced apart from the first target image sensor or the second target image sensor by a predetermined distance; 
 a controller connected to the first target image sensor and the second target image sensor, 
 wherein, in an alignment measurement of the first stage and the second stage, the first stage and the second stage are movable so that the first target image sensor and the second target image sensor face each other and the target plate is between the first target image sensor and the second target image sensor facing each other, and 
 wherein the controller is configured to control operations of the first stage and the second stage based on results of the alignment measurement of the first stage and the second stage. 
 
     
     
       2. The wafer bonding apparatus as claimed in  claim 1 , wherein:
 the first target image sensor is on a first outer portion of the first stage, and 
 the second target image sensor is on a fourth outer portion of the second stage, the fourth outer portion being opposite to a third outer portion of the second stage and the third outer portion being aligned with the first outer portion of the first stage. 
 
     
     
       3. The wafer bonding apparatus as claimed in  claim 1 , wherein, in the alignment measurement of the first stage and the second stage, each of a first distance between the target plate and the first target image sensor and a second distance between the target plate and the second target image sensor is within a range of 5 mm to 15 mm. 
     
     
       4. The wafer bonding apparatus as claimed in  claim 3 , wherein the first distance and the second distance are equal to each other. 
     
     
       5. The wafer bonding apparatus as claimed in  claim 1 , wherein the target plate includes an alignment target in a plane parallel to the first surface and the second surface. 
     
     
       6. The wafer bonding apparatus as claimed in  claim 1 , wherein the target portion includes:
 a base plate extending outwardly from the outer portion of the first stage or the second stage; 
 a support plate extending in a vertical direction from the base plate; and 
 the target plate fixed to the support plate. 
 
     
     
       7. The wafer bonding apparatus as claimed in  claim 1 , further comprising:
 a first mark image sensor on the outer portion of the first stage, the first mark image sensor being configured to image a second alignment mark on the second wafer; and 
 a second mark image sensor on the outer portion of the second stage, the second mark image sensor being configured to image a first alignment mark on the first wafer. 
 
     
     
       8. The wafer bonding apparatus as claimed in  claim 7 , wherein each of the first mark image sensor and the second mark image sensor includes a macro camera and a micro camera. 
     
     
       9. The wafer bonding apparatus as claimed in  claim 7 , wherein, when the target portion is fixedly installed on the first stage, the second mark image sensor is also the second target image sensor. 
     
     
       10. A wafer bonding apparatus, comprising:
 a first stage configured to suction a first wafer; 
 a second stage configured to suction a second wafer; 
 a stage driver configured to move the first stage and the second stage relative to each other; 
 a first mark image sensor on an outer portion of the first stage, the first mark image sensor being configured to image a second alignment mark on the second wafer; 
 a second mark image sensor on an outer portion of the second stage, the second mark image sensor being configured to image a first alignment mark on the first wafer; 
 a target image sensor on the outer portion of the first stage adjacent to the first mark image sensor; and 
 a target portion on the outer portion of the first stage, the target portion having a target plate arranged above the target image sensor and spaced apart from the target image sensor by a predetermined distance, 
 wherein: 
 in an alignment measurement of the first stage and the second stage, the first stage and the second stage are movable so that the target image sensor and the second mark image sensor face each other and the target plate is between the target image sensor and the second mark image sensor facing each other, and 
 each of a first distance between the target plate and the target image sensor and a second distance between the target plate and the second mark image sensor is within a range of 5 mm to 15 mm. 
 
     
     
       11. The wafer bonding apparatus as claimed in  claim 10 , wherein the first distance and the second distance are equal to each other. 
     
     
       12. The wafer bonding apparatus as claimed in  claim 10 , wherein:
 the first mark image sensor and the target image sensor are on a first outer portion of the first stage, and 
 the second mark image sensor is on a fourth outer portion of the second stage, the fourth outer portion being opposite to a third outer portion of the second stage and the third outer portion being aligned with the first outer portion of the first stage. 
 
     
     
       13. The wafer bonding apparatus as claimed in  claim 10 , wherein the target plate includes an alignment target in a plane parallel to surfaces of the first wafer and the second wafer. 
     
     
       14. The wafer bonding apparatus as claimed in  claim 10 , wherein the target portion includes:
 a base plate extending outwardly from the outer portion of the first stage; 
 a support plate extending in a vertical direction from the base plate; and 
 the target plate fixed to the support plate. 
 
     
     
       15. The wafer bonding apparatus as claimed in  claim 10 , wherein each of the first mark image sensor and the second mark image sensor includes a macro camera and a micro camera. 
     
     
       16. The wafer bonding apparatus as claimed in  claim 10 , wherein, in the alignment measurement of the first stage and the second stage, the target image sensor and the second mark image sensor capture an image of an alignment target of the target plate. 
     
     
       17. The wafer bonding apparatus as claimed in  claim 10 , further comprising:
 a push rod that is movable upwardly and downwardly through a center hole in a middle portion of at least one of the first stage and the second stage to press a middle region of the first wafer or the second wafer; and 
 a push rod driver configured to move the push rod upwardly and downwardly. 
 
     
     
       18. The wafer bonding apparatus as claimed in  claim 10 , further comprising a controller connected to the first mark image sensor, the second mark image sensor, and the target image sensor, the controller being configured to control operations of the first stage and the second stage based on results of an alignment measurement of the first wafer and the second wafer obtained by the first mark image sensor and the second mark image sensor and results of the alignment measurement of the first stage and the second stage obtained by the target image sensor and the second mark image sensor. 
     
     
       19. A wafer bonding apparatus, comprising:
 a first stage configured to suction a first wafer; 
 a second stage configured to suction a second wafer; 
 a stage driver configured to move the first stage and the second stage relative to each other; 
 a first mark image sensor on an outer portion of the first stage, the first mark image sensor being configured to image a second alignment mark on the second wafer; 
 a second mark image sensor on an outer portion of the second stage, the second mark image sensor being configured to image a first alignment mark on the first wafer; 
 a target image sensor in the outer portion of the first stage adjacent to the first mark image sensor; 
 a target portion on the outer portion of the first stage, the target portion having a target plate arranged above the target image sensor and spaced apart from the target image sensor by a predetermined distance; 
 a push rod that is movable upwardly and downwardly through a center hole in a middle portion of at least one of the first stage and the second stage to press a middle region of the first wafer or the second wafer; and 
 a push rod driver configured to move the push rod upwardly and downwardly, 
 wherein, in an alignment measurement of the first stage and the second stage, the first stage and the second stage are movable so that the target image sensor and the second mark image sensor face each other and the target plate is between the target image sensor and the second mark image sensor facing each other.